Differential Pressure Measuring Transducer Unit

ABSTRACT

The disclosure relates to a differential pressure transducer unit comprising an over-load protection system which is used to measure low differential pressure in liquids and gases under high static pressure load which can be connected to flanges on the working pressure lines. The differential pressure transducer unit consists of a planar multi-layered arrangement comprising layers which are conductive, insulating and which are insulated from each other, whereby the insulating and conductive layers comprises recesses which at least partially cover each other, wherein the measuring mechanism and the measuring value processing means are accommodated. At least one of the layers is a functional component of the over-load protection system.

The invention relates to a differential pressure measuring transducerunit for measuring a small differential pressure in liquids and gasesunder a high static pressure load, which can be connected to the activepressure lines by flanges.

Such devices are known by prior use and from relevant publications.Their basic mechanical structure is described in detail in GB 2 065 893and EP 0 143 702. Irrespective of the type of conversion of mechanicalpressure/differential pressure signals into equivalent electricalquantities, the two prior publications provide an essentiallycylindrical central body which is enclosed between two similarbowl-shaped caps by using appropriate sealing means. These caps arescrewed together by a multiplicity of radially arranged and mechanicallyprestressed bolts, the mechanical prestress of the bolts being selectedso as to avoid a pressure loss at the central body under the maximallypermissible static pressure load.

Owing to this mechanical prestress inherent in the principle, whichvaries individually from device to device, a mechanical prestress of thecentral body occurs which causes a prestress-dependent offset or aprestress-dependent characteristic curve deformation of the measuring oroverload membrane extending over a midplane of the central body.Furthermore, the required seals are to be adapted to the device inrespect of their material composition as a function of the processmedium, and they are moreover susceptible to wear.

Each cap comprises a recess on the central body side, which is connectedto flange terminals via channels, which are usually configured as bores.The mid-spacing of these channels is dictated by standardization on theflange terminals.

The central body axisymmetrically comprises a neck on which a head partis fastened, in which means for measured value conversion, processingand display are provided according to GB 2 065 893.

The multiplicity of required pressure-tight assembly points of the knownpressure measuring devices requires precision processing to be machinedextensively at a multiplicity of individual points.

Furthermore, WO 88/02107 discloses a pressure measuring device whichconsists of a cylindrical base body on which tangential flow terminals,between which the pressure sensor lies, are provided on one side.Although this device has a smaller number of pressure-tight assemblypoints, its type of mounting is constrained with a fixed allocation ofthe display means to the device position.

A particular problem of such measuring devices with an overloadprotection system, which is intended to protect the sensitivedifferential pressure sensor from damage in the event of a unilateralpressure drop, in which case the static pressure is applied as adifferential pressure, resides in the electrical connection of thesensor elements to downstream measured value processing means. To thisend, Hartmann & Braun list sheet 10/15-6.21, October 1992 edition,discloses a measuring transducer in which the measuring capsulecomprising the measuring mechanism is suspended from an axisymmetricallyextending overload membrane. The measuring mechanism arranged mobilerelative to the package on the overload membrane requires flexibleconnection lines, which are also stressed in their flexibility, and atleast two pressure-tight resilient feeds for each connection line, oneof which leads out of the measuring mechanism and another of which leadsout of the package which encloses the pressure space.

Particularly in the case of self-correcting differential pressuremeasuring transducer units which, besides the differential pressuresensor, also comprise an absolute pressure sensor and a temperaturesensor to compensate for pressure- and the temperature-dependentmeasurement errors, a high outlay is thus required for the electricalconnection technology, which moreover reduces the long-term reliability.

Furthermore, the known differential pressure measuring transducer unitsare characterized by an elaborate multi-part and specialized structure,which is produced by miscellaneous assembly technologies.

It is therefore an object of the invention, in an overload-protecteddifferential pressure measuring transducer unit of the type mentioned inthe introduction, to reduce the number of pressure-tight resilient feedsand substantially obviate permanently stressed flexible connectionlines.

According to the invention, this object is achieved by the means ofpatent claim 1. Advantageous refinements of the invention are describedin patent claims 2 to 15.

The invention is based on a differential pressure measuring transducerunit with an overload protection system for its measuring mechanism,having at least one sensor, in which the measuring mechanism isconnected via pressure-tight electrical feeds to measured valueprocessing means and in which a pressure averager spatially separatedfrom the process medium is applied to the measuring mechanism.

The essence of the invention consists in a planar multi-layeredarrangement consisting of insulating layers and conductive layersinsulated from one another, which comprise partially overlappingrecesses into which the measuring mechanism and the measured valueprocessing means are fitted. Furthermore, at least one of the layers isa functional component of the overload system.

Although multi-layered arrangements consisting of insulating layers andconductive layers insulated from one another are known in principle inthe form of multi-layered circuit boards as support elements forelectronic components in printed circuits, it has surprisingly beenshown that the carrier material is suitable as a functional element inthe overload protection system of a differential pressure measuringtransducer unit.

The starting point of the multi-layered arrangement is a circuit boardknown per se, consisting of a supporting insulator layer and at leastone conductive layer structured in the form of interconnections. Themeasuring mechanism and the measured value processing means are mountedon this circuit board. Further equivalent insulating layers andconductive layers insulated from one another are stacked on at least oneside of this circuit board.

The electrical connections between the measuring mechanism and themeasured value processing means are configured as patterns in theconductive layer of the circuit board. Permanently stressed flexibleconnection lines are thereby fully obviated.

By virtue of the lateral structure of the mechanical layout, thepressure-tight electrical leads are guided along the layers whileobviating layer penetrations. This fully obviates additional technicalmeans for leading electrical lines out of pressurized spaces intopressure-free spaces. The number of pressure-tight resilient feeds istherefore made insignificant.

According to one feature of the invention, one of the inner insulatinglayers is designed as a membrane of the overload protection system ofthe differential pressure measuring transducer unit.

According to an alternative feature of the invention, one of the innerconductive layers is designed as a membrane of the overload protectionsystem of the differential pressure measuring transducer unit. Thismeasure minimizes the risk of irreversible deformation of the membraneunder a static overload.

Advantageously, the constituents of the package of the measuringmechanism and of the measured value processing means, the supportelements for the measured value processing means including theelectrical connection means as well as the constituents of the overloadprotection system, are made from the same material combination and areassembled according to a uniform method.

Supporting and functional elements are particularly advantageouslycombined in the same component. This component is produced by atechnologically undemanding process known per se.

Other details and advantages of the invention will be explained in moredetail below with reference to exemplary embodiments. In the requisitedrawings:

FIG. 1 shows a sectional representation of a first embodiment of adifferential pressure measuring transducer unit

FIG. 2 shows a sectional representation of a second embodiment of adifferential pressure measuring transducer unit

FIG. 3 shows a sectional representation of a third embodiment of adifferential pressure measuring transducer unit

FIG. 4 shows a sectional representation of a differential pressuremeasuring transducer

FIG. 1 shows a sectional representation of the essential constituents ofa differential pressure measuring transducer unit in a first embodiment.The differential pressure measuring transducer unit consists essentiallyof a stack of insulating layers 21 to 25 and conductive layers 11 to 15insulated from one another, which comprise partially overlappingrecesses 31 to 37, into which a measuring mechanism 60 and measuredvalue processing means 80 are fitted.

In this first embodiment, the insulating layer 21 comprises twoidentical funnel-shaped recesses 31 and 32. The outside of theinsulating layer 21 is covered by the conductive layer 11, which isconfigured as a separating membrane 51 and 52 in the region of therecesses 31 and 32. The separating membranes 51 and 52 are preferablyembossed in the form of a concentric corrugated pattern known per se.The process pressures act on the other side of the separating membranes51 and 52 from the insulating layer 21.

The insulating layers 22 and 24 separated from one another by theinsulating layer 23 comprise congruent recesses 33 and 34. In theoverlap region of the recesses 33 and 34, the insulating layer 23 isconfigured as a membrane. The recess 33 is connected to thefunnel-shaped recesses 32 via a channel 42. The recess 34 is connectedto the funnel-shaped recess 31 via a channel 41.

The insulating layers 23 and 24 as well as the conductive layer 14furthermore comprise partially overlapping recesses 35 and 36, intowhich the measuring mechanism 60 is fitted. The measuring mechanism 60is connected pressure-tightly to the insulating layer 24. The conductivelayer 14 is patterned with openings. The measuring mechanism 60comprises electrical terminals, which are connected via bondingconnections 70 to various patterns of the conductive layer 14. Therecess 35 is connected via the aforementioned channel 41 to thefunnel-shaped recesses 31 and the recess 34. The recess 36 is connectedvia a channel 43 to the recess 33 and in continuation via the channel 42to the funnel-shaped recess 32.

The channels 41 to 43 are configured as recesses of the conductivelayers 13 and 14 arranged between the insulating layers 22, 23 and 24.

The membrane 50 and the recesses 33 and 34 constitute the overloadsystem of the differential pressure measuring transducer unit. Thedifference in the process pressure acting on the separating membranes 51and 52 deflects the separating membranes 51 and 52 while increasing ordecreasing the free volumes of the recesses 33 and 34. The volumedifference is equalized via the channels 41 to 43 into the sensorchambers 35 and 36 and the recesses 33 and 34. In the event of anoverload, the membrane 50 is deflected pressure-dependently.

The insulating layers 22 and 23 as well as the conductive layer 13furthermore comprise overlapping recesses 37, into which the measuredvalue processing means 80 are fitted. In this embodiment, the recess 37is closed on all sides so that the measured value processing means 80are embedded while being protected against mechanical damage. Themeasured value processing means 80 are electrically and mechanicallyconnected to track-shaped patterns of the conductive layer 14.

The conductive layers 12 and 15, arranged between the insulating layers21 and 22 as well as 24 and 25, are designed as shielding surfaces forshielding the measuring mechanism 60 and the measured value processingmeans 80 from electromagnetic radiation.

In particular, it is proposed that the conductive layers 12 to 15 shouldconsist of copper and the insulating layers 21 to 25 should consist offiber-reinforced synthetic resin. For the conductive layer 11, stainlesssteel is preferred.

Starting with a base circuit board consisting of the insulating layer 24and the conductive layer 14, during the production of the differentialpressure measuring transducer unit, further insulating and conductivelayers are applied according to the structure described above with theinterposition of an adhesion promoter, and the entire stack ishot-pressed together.

In a preferred embodiment an adhesive film known per se, consisting ofsynthetic resin, is provided as the adhesion promoter. As analternative, it may be proposed for the differential pressure measuringtransducer unit to be constructed from a stack of synthetic resin platescovered with copper on both sides, and for solder to be provided as theadhesion promoter.

The recesses 31 to 36 as well as the channels 41 to 43 are filled with asubstantially incompressible fluid, in particular silicone oil. Thefluid is introduced into the cavities via capillaries 53 and 54represented in FIG. 3. After filling, the capillaries 53 and 54 areclosed pressure-tightly.

Using the same references for means which are the same, FIG. 2 shows asecond embodiment of the differential pressure measuring transducer unitaccording to the invention. The differential pressure measuringtransducer unit consists essentially of a stack of insulating layers 21to 25 and conductive layers 11 to 16 insulated from one another, whichcomprise partially overlapping recesses 31 to 37, into which a measuringmechanism 60 and measured value processing means 80 are fitted.

In this second embodiment, the insulating layers 21 and 25 respectivelycomprise a funnel-shaped recess 31 and 32 which lie symmetricallyopposite. The outside of the insulating layer 21 is covered by theconductive layer 11 and the outside of the insulating layer 25 iscovered by the conductive layer 16. In the region of the recesses 31 and32, the conductive layers 11 and 16 are configured as a separatingmembrane 51 and 52. The separating membranes 51 and 52 are preferablyembossed in the form of a concentric corrugated pattern known per se.The process pressures act on the other side of the separating membrane51 from the insulating layer 21 and on the other side of the separatingmembrane 52 from the insulating layer 25.

The insulating layers 22 and 24 separated from one another by theinsulating layer 23 comprise congruent recesses 33 and 34. In theoverlap region of the recesses 33 and 34, the insulating layer 23 isconfigured as a membrane 50. The recess 33 is connected to thefunnel-shaped recess 32. The recess 34 is connected to the funnel-shapedrecess 31.

The insulating layers 23 and 24 as well as the conductive layer 14furthermore comprise partially overlapping recesses 35 and 36, intowhich the measuring mechanism 60 is fitted. The measuring mechanism 60is connected pressure-tightly to the insulating layer 24. The conductivelayer 14 is patterned with openings. The measuring mechanism 60comprises electrical terminals, which are connected via bondingconnections 70 to various patterns of the conductive layer 14. Therecess 35 is connected via a channel 41 to the recess 34 and incontinuation to the funnel-shaped recesses 31. The recess 36 isconnected via a channel 43 to the recess 33 and in continuation to thefunnel-shaped recess 32.

The channels 41 to 43 are configured as recesses of the conductivelayers 13 and 15 arranged between the insulating layers 22 and 23 aswell as 24 and 25.

The membrane 50 and the recesses 33 and 34 constitute the overloadsystem of the differential pressure measuring transducer unit. Thedifference in the process pressure acting on the separating membranes 51and 52 deflects the separating membranes 51 and 52 while increasing ordecreasing the free volumes of the recesses 33 and 34. The volumedifference is equalized into the recesses 33 and 34 and via the channels41 to 43 into the measuring mechanism chambers 35 and 36. In the eventof an overload, the membrane 50 is deflected pressure-dependently.

The insulating layers 21, 22 and 23 as well as the conductive layers 11,12 and 13 furthermore comprise overlapping recesses 37, into which themeasured value processing means 80 are fitted. In this embodiment, therecess 37 is open on one side so that the measured value processingmeans 80 are accessible but still embedded while being substantiallyprotected against mechanical damage. The measured value processing means80 are electrically and mechanically connected to track-shaped patternsof the conductive layer 14.

The conductive layers 12 and 15, arranged between the insulating layers21 and 22 as well as 24 and 25, are designed as shielding surfaces forshielding the measuring mechanism 60 and the measured value processingmeans 80 from electromagnetic radiation.

In particular, it is proposed that the conductive layers 12 to 15 shouldconsist of copper and the insulating layers 21 to 25 should consist offiber-reinforced synthetic resin. For the conductive layers 11 and 16,stainless steel is preferred.

Starting with a base circuit board consisting of the insulating layer 24and the conductive layer 14, during the production of the differentialpressure measuring transducer unit, further insulating and conductivelayers are applied according to the structure described above with theinterposition of an adhesion promoter, and the entire stack ishot-pressed together.

In a preferred embodiment an adhesive film known per se, consisting ofsynthetic resin, is provided as the adhesion promoter. As analternative, it may be proposed for the differential pressure measuringtransducer unit to be constructed from a stack of synthetic resin platescovered with copper on both sides, and for solder to be provided as theadhesion promoter.

The recesses 31 to 36 as well as the channels 41 to 43 are filled with asubstantially incompressible fluid, in particular silicone oil. Thefluid is introduced into the cavities via capillaries 53 and 54represented in FIG. 3. After filling, the capillaries 53 and 54 areclosed pressure-tightly.

Using the same references for means which are the same, FIG. 3 shows athird embodiment of the differential pressure measuring transducer unitaccording to the invention. The differential pressure measuringtransducer unit in this third embodiment also consists essentially of astack of insulating layers 21 to 26 and conductive layers 11 to 16insulated from one another, which comprise partially overlappingrecesses 31 to 37, into which a measuring mechanism 60 and measuredvalue processing means 80 are fitted.

In this third embodiment, the insulating layers 21 and 25 respectivelycomprise a funnel-shaped recess 31 and 32 which lie symmetricallyopposite. The outside of the insulating layer 21 is covered by theconductive layer 11 and the outside of the insulating layer 25 iscovered by the conductive layer 16. In the region of the recesses 31 and32, the conductive layers 11 and 16 are configured as a separatingmembrane 51 and 52. The separating membranes 51 and 52 are preferablyembossed in the form of a concentric corrugated pattern known per se.The process pressures act on the other side of the separating membrane51 from the insulating layer 21 and on the other side of the separatingmembrane 52 from the insulating layer 25.

The insulating layers 22 and 24 separated from one another by theconductive layer 17, as well as the insulating layer 26 and theconductive layer 14, comprise congruent recesses 33 and 34. In theoverlap region of the recesses 33 and 34, the conductive layer 17 isconfigured as a membrane 50. The recess 33 is connected to thefunnel-shaped recess 32. The recess 34 is connected to the funnel-shapedrecess 31.

The insulating layers 24 and 26 as well as the conductive layer 14furthermore comprise partially overlapping recesses 35 and 36, intowhich the measuring mechanism 60 is fitted. The measuring mechanism 60is connected pressure-tightly to the insulating layer 24. The conductivelayer 14 is patterned with openings. The measuring mechanism 60comprises electrical terminals, which are connected via bondingconnections 70 to various patterns of the conductive layer 14. Therecess 35 is connected via a channel 41 to the recess 34 and incontinuation to the funnel-shaped recesses 31. The recess 36 isconnected via a channel 43 to the recess 33 and in continuation to thefunnel-shaped recess 32.

The channels 41 to 43 are configured as recesses in the insulatinglayers 22 and 26. The channel-forming recesses are preferably impressedinto the insulating layers 22 and 26.

The membrane 50 and the recesses 33 and 34 constitute the overloadsystem of the differential pressure measuring transducer unit. Thedifference in the process pressure acting on the separating membranes 51and 52 deflects the separating membranes 51 and 52 while increasing ordecreasing the free volumes of the recesses 33 and 34. The volumedifference is equalized into the recesses 33 and 34 and via the channels41 to 43 into the measuring mechanism chambers 35 and 36. In the eventof an overload, the membrane 50 is deflected pressure-dependently.

The insulating layers 25 and 26 as well as the conductive layer 16furthermore comprise overlapping recesses 37, into which the measuredvalue processing means 80 are fitted. In this embodiment, the recess 37is open on one side so that the measured value processing means 80 areaccessible but still embedded while being substantially protectedagainst mechanical damage. The measured value processing means 80 areelectrically and mechanically connected to track-shaped patterns of theconductive layer 14.

The conductive layer 17, arranged between the insulating layers 22 and24, is designed as a shielding surface for shielding the measuringmechanism 60 and the measured value processing means 80 fromelectromagnetic radiation.

A recess 38 is furthermore provided, which in this third embodiment isarranged congruently in the insulating layers 22 and 24 to 26 as well asin the conductive layers 14, 16 and 17. The ends of two capillaries 53and 54, the opposite ends of which respectively extend into the recesses33 and 34, are fitted as measuring transducer-specific equipmentelements in this recess 38.

In particular, it is proposed that the conductive layers 14 and 17should consist of copper and the insulating layers 21 to 26 shouldconsist of fiber-reinforced synthetic resin. For the conductive layers11 and 16, stainless steel is preferred.

Starting with a base circuit board consisting of the insulating layer 24and the conductive layer 14, during the production of the differentialpressure measuring transducer unit, further insulating and conductivelayers are applied according to the structure described above with theinterposition of an adhesion promoter, and the entire stack ishot-pressed together.

Irrespective of the embodiment, before the insulating layer 21 isapplied, the capillary 53 is introduced so that the one tube endprojects into the recess 34 and the other tube end projects into therecess 38. Before the insulating layer 25 is applied, the capillary 54is introduced so that one tube end projects into the recess 33 and theother tube end projects into the recess 38.

In a preferred embodiment an adhesive film known per se, consisting ofsynthetic resin, is provided as the adhesion promoter.

The recesses 31 to 36 as well as the channels 41 to 43 are filled with asubstantially incompressible fluid, in particular silicone oil. Thefluid is introduced into the cavities via capillaries 53 and 54. Afterfilling, the capillaries 53 and 54 are closed pressure-tightly.

Lastly, FIG. 4 shows a sectional representation of a differentialpressure measuring transducer having a differential pressure measuringtransducer unit according to FIG. 2. In this case, the differentialpressure measuring transducer unit is clamped between two flange caps90, which bear on the outer conductive layers 11 and 16.

Each flange cap 90 comprises a bore 91 whose opening that faces awayfrom the differential pressure measuring transducer unit is equippedwith a flange appendage 92. The bore 91 in the flange cap 90 is arrangedin the region of the separating membranes 51 and 52 of the differentialpressure measuring transducer unit. Each bore 91 in the flange cap 90 isassigned two threaded bores 93, which are configured as blind bores.

The flange caps 90 are screwed together by a multiplicity of bolts 95,which are distributed uniformly over the circumference of thedifferential pressure measuring transducer unit. To this end, one of theflange caps 90 comprises bores and the opposite flange cap 90 comprisescorresponding threaded bores.

For correct use of the differential pressure measuring transducer, animpulse line is attached to each flange cap 90. The impulse linesrespectively comprise a flange-like collar, which is held by means of aunion plate in the flange appendage 92. The union plate is fastened onthe flange cap 90 by screws, which engage into the threaded bores 93.

LIST OF REFERENCES

-   11 to 17 conductive layer-   21 to 26 insulating layer-   31 to 38 recess-   41 to 43 channel-   50 membrane-   51, 52 separating membrane-   53, 54 capillary-   60 measuring mechanism-   70 bonding connection-   80 measured value processing means-   90 flange cap-   91 bore-   92 flange appendage-   93 threaded bore-   95 bolt

1. A differential pressure measuring transducer unit with an overloadprotection system for its measuring mechanism, having at least onesensor, in which the measuring mechanism is connected via pressure-tightelectrical feeds to measured value processing means and in which apressure average spatially separated from the process medium is appliedto the measuring mechanism, wherein a planar multi-layered arrangementconsisting of insulating layers and conductive layers insulated from oneanother is provided, the insulating and conductive layers of whichcomprise partially overlapping recesses into which the measuringmechanism and the measured value processing means are fitted, andwherein at least one of the layers is a functional component of theoverload system.
 2. The differential pressure measuring transducer unitas claimed in claim 1, wherein the insulating and conductive layers ofthe multi-layered arrangement are assembled together with theinterposition of an adhesion promoter and by pressure application. 3.The differential pressure measuring transducer unit as claimed in claim2, wherein the adhesion promoter is solder.
 4. The differential pressuremeasuring transducer unit as claimed in claim 1, wherein one of theinsulating layers is designed as a membrane of the overload protectionsystem.
 5. The differential pressure measuring transducer unit asclaimed in claim 1, wherein one of the conductive layers is designed asa membrane of the overload protection system.
 6. The differentialpressure measuring transducer unit as claimed in claim 1, wherein atleast one of the conductive layers is designed as a separating membraneof the overload protection system.
 7. The differential pressuremeasuring transducer unit as claimed in claim 1, wherein at least one ofthe insulating layers comprises at least one essentially conical recess,which is covered with the separating membrane of the overload protectionsystem so as to form a chamber.
 8. The differential pressure measuringtransducer unit as claimed in claim 1, wherein the insulating layersconsist of fiber-reinforced synthetic resin.
 9. The differentialpressure measuring transducer unit as claimed in claim 1, wherein theinner conductive layers, arranged between insulating layers, consist ofcopper.
 10. The differential pressure measuring transducer unit asclaimed in claim 1, wherein the outer conductive layers, arranged oninsulating layers consist of stainless steel.
 11. The differentialpressure measuring transducer unit as claimed in claim 1, wherein atleast two inner insulating layers separated from one another comprisecongruent recesses which are closed by neighboring layers so as to forma respective chamber.
 12. The differential pressure measuring transducerunit as claimed in claim 1, wherein at least two of the inner layersrespectively comprise an at least partially congruent recess so as toform a sensor chamber, in which the pressure sensor is fitted.
 13. Thedifferential pressure measuring transducer unit as claimed in claim 1,wherein at least two of the inner conductive layers comprise lateralrecesses, which respectively form a channel.
 14. The differentialpressure measuring transducer unit as claimed in claim 1, wherein atleast two of the inner insulating layers comprise lateral recesses,which respectively form a channel.
 15. The differential pressuremeasuring transducer unit as claimed in claim 1, wherein the sensorchamber and the chambers are connected via a channel.
 16. Thedifferential pressure measuring transducer unit as claimed in claim 3,wherein one of the insulating layers is configured as a membrane of theoverload protection system.
 17. The differential pressure measuringtransducer unit as claimed in claim 3, wherein one of the conductivelayers is configured as a membrane of the overload protection system.18. The differential pressure measuring transducer unit as claimed inclaim 5, wherein at least one of the conductive layers is configured asa separating membrane of the overload protection system.
 19. Thedifferential pressure measuring transducer unit as claimed in claim 6,wherein at least one of the insulating layers comprises at least oneessentially conical recess, which is covered with the separatingmembrane of the overload protection system so as to form a chamber. 20.The differential pressure measuring transducer unit as claimed in claim7, wherein the insulating layers comprised of fiber-reinforced syntheticresin.
 21. The differential pressure measuring transducer unit asclaimed in claim 8, wherein the inner conductive layers, arrangedbetween insulating layers, comprised of copper.
 22. The differentialpressure measuring transducer unit as claimed in claim 9, wherein theouter conductive layers, arranged on insulating layers comprised ofstainless steel.
 23. The differential pressure measuring transducer unitas claimed in claim 10, wherein at least two inner insulating layersseparated from one another comprise congruent recesses which are closedby neighboring layers so as to form a respective chamber.
 24. Thedifferential pressure measuring transducer unit as claimed in claim 10,wherein at least two of the inner layers respectively comprise an atleast partially congruent recess so as to form a sensor chamber, inwhich the pressure sensor is fitted.
 25. The differential pressuremeasuring transducer unit as claimed in claim 10, wherein at least twoof the inner conductive layers comprise lateral recesses, whichrespectively form a channel.
 26. The differential pressure measuringtransducer unit as claimed in claim 10, wherein at least two of theinner insulating layers comprise lateral recesses, which respectivelyform a channel.
 27. The differential pressure measuring transducer unitas claimed in claim 14, wherein the sensor chamber and the chambers areconnected via a channel.
 28. A differential pressure measuringtransducer unit, comprising: an overload protection system for ameasuring mechanism; measured value processing means, in which themeasuring mechanism is connected via pressure-tight electrical feeds tothe measured value processing means; and a planar multi-layeredarrangement, wherein insulating and conductive layers form partiallyoverlapping recesses into which the measuring mechanism and the measuredvalue processing means are fitted.